Electrical switch



July 21, 1942. w. H. HIRSCHFELD ELECTRICAL SWITCH Filed Dec. 4, 1940 fzaezozaz v ZWH EIE] Patented July 21, 1942 ELECTRICAL SWITCH Walter H. Hirschfeld, Chicago, 111., assignor to Max Levey, Chicago, Ill.

Application December 4, 1940, Serial N 0. 268,453

(Cl. 2il(l52) 1 Claim.

This invention relates to electrical switches generally and more particularly to an improved film driven or driving rotary electrical switch adapted to be used in connection with apparatuses utilizing strips of film passing a given point, such as for example motion picture projectors.

In motion picture projectors which are adapted to be coin operated, the fact that such projectors are to be used in stores, restaurantsand the like, as a collateral source of revenue, the necessity of providing an attendant for starting and stopping the projector at the beginning or end of a subject is obviously undesirable.

Means have been provided on such coin operated projectors whereby the projection machine is initiated by means of a coin operated switch, many examples of which are well known in the art, but the difficulty which has arisen has been in stopping the projection of any subject at the completion thereof, and the poising of the projector in readiness for its subsequent use. Means have been provided for this latter difficulty requiring the use of critical micro switches adapted to fall into notches provided in the film edge. The disadvantages of this are obvious when it is realized that the thickness of film varies with wear and that the position of the film on the driving sprockets also varies over periods of time, making operation uncertain and undependable.

Another point to be considered is the weakening of the film by the use of such notches and the rough wear to which film in unattended projection machines may be subjected.

Other means having obvious disadvantages consist of applying metallic foil along edges of the film at appropriate places and causing same to run between pairs of metallic rollers thereby completing electrical circuits.

It is the object of this invention to provide a new and improved simple, positively operating rotary electrical circuit completing device capable of use with any type of moving film.

A further object of the present invention is to provide a switch of the character described which will be rugged in its construction and non-critical and positive in its operation.

A further object of the present invention is to provide a switch of the character described which may be constructed from a minimum of parts and easily installed in any type of known projector.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features of construction, arrangement and combination of parts hereinafter fully described, illustrated in the accompanying drawing, and particularly pointed out in the appended claim, it being understood that various changes in the form, proportion, size and minor details of the structure may be made without departing from the spirit or sacrificing anyof the advantages of the invention.

For the purpose of facilitating an understanding of my invention, I have illustrated in the accompanying drawing a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, my invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawing in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawing:

Fig. 1 is a side elevational View of my improved switch showing parts in section and having a representative circuit connected thereto.

Fig. 2 is a front elevational view of my improved switch mechanism with part of the sprocket wheel in section.

Fig. 5 is a plan view of a fragment of a type of film adapted to be used with my new device.

Referring to the construction more specifically, the reference character Ill designates generally a support of insulating material upon which the parts of the switch per se are adapted to be fastened. The support I0 may consist of an insulating plate attached to the wall of a projector where the wall may be made of metal. A bearing II is fixed in the support Ill and has a shaft I2 journalled therein. Said shaft I2 may be a sprocket driving shaft of the projector. 011 the end of the shaft l2 there is provided a sprocket wheel l3 having a plurality of sprocket teeth [4 adapted to engage into the sprocket openings or perforations I5 of the film I6 in a conventional and well known manner. The film is thus driven or pulled across appropriate optical trains (not shown) to cause the projection of the pictures, or other matter which may be provided in the panels ll thereof, upon a screen (not shown).

It will be noted that the sprocket wheel l3 provides said teeth l4 along two edges thereof as is conventional.

In accordance with my invention, I have provided the sprocket wheel IS with a plurality of recesses or wells l8, arranged between various pairs of sprockets or teeth l4 thereof along the left edge as seen in Fig. I. Said wells have spring actuated metallic plungers 19 disposed therein and urged radially outward by means of springs 23 associated therewith. The wells are provided at their outermost ends with guiding plug members 2| permitting free outward passage of the plungers I9 radially and, if desired, limiting such radial movement.

It will be obvious that as film of the type shown in Fig. 3 is caused to move past the member I3 the same will force the plungers I9 into their respective wells I8 during said passage unless means is provided between the perforations I to permit radial movement of the said plungers It. Consequently I provide a number of circular openings 22 in the film at appropriate places where it is desired that electrical contact be made, such as for example at the end of a subject printed in the panels I! of the film when it is desired to shut 01f the driving motor or during the projection of a subject when it is I desired that certain effects be obtained, as for example, sound or lighting effects operated electrically and initiatable by means of electrical circuit completion. Likewise, said effects may be in similar manner discontinued by means of my device, or a plurality of same cooperating with appropriately placed openings 22 provided in the film It. The existence of the circular openings 22 causes the spring actuated plungers I9 to project outwardly and through the film for a purpose to be presently described.

Disposed to one side of the rotary sprocket Wheel I3 and insulated therefrom, I provide a bracket 23 fixed to the support If] by screws 24 or the like. The bracket 23 may be made of metal and the screws 24 may be made of metal as well to provide contact for an external electrical circuit. The end of the bracket 23 has a screw threaded contact member 25 movably arranged in an appropriate opening or recess provided therein and adjustable towards or away from the rotary sprocket wheel I3 by means of the slotted head 26 and said screw threading. ,A set screw 21 is provided to fix any given position of the contact 25.

The contact 25 is adjusted so that it normally clears the film and sprocket teeth during ordinary motion thereof past the sprocket wheel I3. This is clearly shown in Fig. 2. However, when the round openings 22 of the film are reached, as for example at the end of any given subject, the plungers I9 will project through the film sumciently far enough to contact against the tip of the contact member 25.

It will be noted that the sprocket wheel I3 is made of metal and consequently its shaft I2 is adapted to act as a conductor establishing connection between the spring actuated plungers I9 and the bearing II. A contact screw 28 is associated with the bearing and adapted to have one of the leads of the external electrical circuit connected thereto. This means of electrical connection is, of course, arbitrary, it being practicable to utilize brush means or the like for similar purposes,

I have illustrated in Fig. 1 the type of circuit adapted to be used with my new electrical switch. One of the screws 24 is connected to a lead 29 and the screw 23 is connected to the lead 39. The lead 33 is connected to one side of a power line 3I and the lead 29 is connected to the other side of the power line 31 through the coil 32 of a relay 33. The lead from the'coil to the line is designated 34. A motor 35 is connected across the line 3i through a switch 36 which is provided with a movable arm 31 adapted to be actuated by the relay 33. A second relay 38 is connected across the line by means of the leads 39 and 40 within which the coil M of said relay 38 is connected. A switch 42 is connected in series with the lead 49.

It will be noted that the sprocket wheel I have illustrated is provided with ten (10) pairs of sprocket teeth, the left edge being the only one provided with the spring actuated plungers I9. Five (5) plungers are provided to establish the required contact. It is, of course, obvious that contact need only be made once, but the plungers are disposed about the periphery of the sprocket wheel I3 to assure such contact regardless of the rotatory disposition of the wheel at the time that the series of round perforations 22 pass same. It will further be noted that the series of round perforations is provided on the film with each perforation being disposed between consecutive pairs of sprocket perforations I5, Whereas the sprocket wheel I3 is provided with a plunger between alternate pairs of sprockets It. The purpose of this is again to assure contact. It will be seen, therefore, that if the switch is acting properly, a series of six (6) round perforations, as shown in Fig. 3, will give a series of three (3) electrical contacts. It is obvious that the number of sprockets, plungers, or perforations on the film is entirely a matter of choice, and it is not intended that the invention be limited to the quantities shown or suggested.

It should also be obvious that the contact device shown in the figures, namely the bracket 23 and the pin 25 is also capable of wide variation and may consist of any contacting means, such as brush means, resilient contacts, mercury pools and the like adapted to be disposed spaced from the surface of the moving film to the top, sides, or bottom of the wheel I3 and contactable by the spring actuated plungers I9 when same are allowed to pass through the film by means of the perforations 22.

Referring to Fig. 1, the device, as utilized with coin operated projectors, operates as follows:

A coin is inserted into the machine, closing the switch 42 in any manner well known in the art, causing a surge of current from the line 3| through the relay ll by means of the leads 39 and 49. The arm 43 is pulled to the right as viewed in Fig. 1 against the tension of the spring 44 out of the path of the arm 2-5 of the relay 33. The arm &5 being released, the spring 43 attached to the end thereof pulls same upwards thereby closing the contacts of the switch 33 and starting the motor 35 which is connected to the ine 3I. The film I3 thereupon passes an optical train and the subject is projected upon an appropriate screen or the like. While the film is passing the rotating sprocket wheel I3, there is no connection made between the leads 23 and 39, since the film itself forces the spring plungers I9 into the respective wells I3 and being of insulating material, insulates the spring plungers I9 from the contact tip 25. After the film has run its length or has reached the end of a subject the perforations 22 which have been previously pro vided therein pass over the sprocket wheel I3, thereby permitting the spring operated plungers I9 to project through the film l6 and contact the contact member 25. At this point electric-a1 connection is established between the leads 29 and 39 as follows:

Lead 33 to screw 23 through bearing II, shaft I2, sprocket wheel I3, spring 29, plunger I9, contact member 25, bracket 23, screw 24 to lead 29.

The circuit being closed, the relay 33 has the coil 32 thereof connected across the line 3| through the leads 34, 29 and 33. Energization of the coil 32 pulls the arm 45 downward against the force of the spring 46, opening the switch 35, and thereby breaking the circuit of the motor 35 from the line 3| stopping said motor and hence stopping the movement of the film. As the arm 45 passes the lower end of the arm 53, the spring 44 pulls the arm 43 into place, blocking upward movement of the arm 45. In this position, the device is inoperative until the necessary insertion of a coin to operate the switch 42. Obviously, with the circuit shown and described, my new circuit completing device is a safety mechanism. If, during the course of operation, the film It should break or burn, the circuit will thereby be completed, automatically shutting oif the motor 35.

It will be noted that the switch which I have described is obviously a simple and efficient one, and it should be appreciated that it is capable of use with any type of moving film or other thin material which may be made to pass over a sprocket or other type of wheel. As has been described, the sprocket wheel may be an actual part of the actuating mechanism driving the film or it may be an auxiliary non-driven wheel riding perforations provided in the film. The film need not be photographic film, but may be any type of insulating material adapted to be used as described.

It will be noted that I have not shown any connection between the driven film and the motor, nor have I shown means whereby a coin may be caused to operate the switch 42. Obviously, such means are not the subject of this invention, and hence are not shown.

It is believed that my invention, its mode of construction and assembly, and many of its advantages should be readily understood from the foregoing without further description, and it should also be manifest that while a preferred embodiment of the invention has been shown and described for illustrative purposes, the structural details are nevertheless capable of wide variation within the purview of my invention as defined in the appended claim.

What I claim and desire to secure by Letters Patent of the United States is:

In a device of the character described, a support member, an electrical contacting member insulatedly attached to said support member, a sprocket wheel having sprocket teeth rotatively mounted on said support member and insulated therefrom and connected with an electrical circuit, said contacting member also being connected to said electrical circuit, said sprocket wheel having a plurality of spring expressed contact plungers adapted to radially protrude therefrom a distance greater than the height of said sprocket teeth, said electrical contacting member being spaced from said sprocket wheel and adapted to clear said teeth but engage said spring expressed contact plungers, said teeth and spring expressed contact plungers being provided only on the margins of said wheel thereby providing an uninterrupted space between said margins of said wheel, an insulating film having sprocket perforations along its margins adapted to engage said sprocket teeth and be guided by said sprocket wheel, said film also having contact plunger openings along its margins between certain of its perforations and in line therewith whereby the points of electrical contact are clear of the main zone of the film between the margins thereof, said contact plunger openings permitting said spring expressed members to protrude therethrough at predetermined times, said film otherwise serving to retain said spring expressed members within said sprocket wheel in non-expressed condition and out of engagement with said electrical contacting member.

WALTER H. HIRSCHFELD. 

